Would like some thoughts are which spur to run?
We are running 21.5 Novak motor and GTB speedo
KSG Gen 2 and an SMC on carpet at the Birds!
Roll out is right around a 3.60
Thoughts?
Thanks!

I have seen alot of other posts about gearing.......we are running a 88 spur on about 2.15 tires.....should we stay with the 88 and just change pinoins?

You should be able to find plenty of help at the snowbirds .......... there's plenty of guys there to help you out and explain which one you should run. running a smaller spur will help free the car up because the motor is further back in the car.

hey try fine the manufacture of your car like hd , ksg le and ask them

A 3.60 rollout would be about a 47/88 w/ 2.15 tires so you still have a lot of room to gear up or down in that range.

Is 3.60 a good rollout for the birds?

....Scarecrow said the track was about 169 ft, I would have actually thought the 21.5 rollout would be closer to a 4.15 - 4.20

Thansk for the info.....we live about an hour form the track. But my son is still in school and I am having to work. So I was trying to figure it out at the house so we could be close when we showed back up to practice/race on thursday. We did practice a bit last night. The 3.60 roll out was from about 5 different people. So that is were that came from and Scarecrow was OK with that.

So really the 88 spur should be ok just up and down on pinion accordingly?

Really appreciate your help!

The 88 should be fine

a 4.15- 4.20 rollout is what I'd be suggesting on a track that size for lap times in the 3.7-3.8 second range

about 3.80 rollout for 4.0's

A 3.5 - 3.60 sounds more like what I'd suggest on 17.5/LIPO

I would start around a 3.70 to 3.80 rollout for 21.5.

Depending on the sharpness of the corners the 3.60 to 3.65 would be a good starting point.

Remember that rollout on BL motors will vary greatly depending on Speedo preference and profile setting on the speedo as well. So if you ask what someone is rolling out also ask what speedo and profile they are using to compare. The all add different amounts of timing on different profiles.

EA

Remember that rollout on BL motors will vary greatly depending on Speedo preference and profile setting on the speedo as well. So if you ask what someone is rolling out also ask what speedo and profile they are using to compare. The all add different amounts of timing on different profiles.

EA

Good point. Also, don't forget to ask if the motor timing has been adjusted. ;)

Chuck